1. Field of the Invention
The present invention relates to a developer regulating member that regulates the thickness of a developer on the surface of a developer carrier provided in an image forming apparatus such as a copying machine, a printer, and a facsimile machine, a developing device having this developer regulating member, a process cartridge, and an image forming apparatus. In addition, the present invention relates to a method for manufacturing the developer regulating member.
2. Description of the Related Art
As a developer regulating member for regulating the thickness of a developer formed on the surface of a developing roller functioning as a developer carrier provided in a developing device of an image forming apparatus, there has conventionally been known a blade-like developer regulating member using a plate-like member.
For example, Japanese Unexamined Patent Application Laid-open No. 2001-92248 describes the configuration in which a layer-thinning blade, which a blade-like developer regulating member for thinning a developer, is caused to abut on the surface of a developer carrier. This layer-thinning blade has a bent portion in which a metallic plate-like member is bent at a predetermined curvature, wherein a surface of the bent portion is caused to abut on a developing roller so that an edge line of the bent portion intersects at right angles with a direction of surface movement of the developing roller. By causing the bent portion to abut on the surface of the developing roller, the abutment pressure on the abutting portion rarely fluctuates and the thickness of the developer passing through the abutting portion can be stabilized, compared to so-called edge abutment for causing a tip end of the plate-like member to abut on the developing roller.
Moreover, according to this publication, the range of the curvature radius of the bent portion of the plate-like member is limited, whereby fixation of the developer that is caused by an excess load imposed on the developer passing through the abutting portion is prevented from occurring, and at the same time a uniform thin layer of the developer can be formed by an appropriate developer regulating force.
However, even if the curvature radius of the bent portion of the plate-like member has not been changed, stripe-like image noise has sometimes occurred depending on the material of the plate-like member due to long-term use. The stripe-like image noise occurs due to the following reason.
Specifically, the outer peripheral surface of the bent portion is stretched by ending the metallic plate-like member, causing surface roughening, i.e., cracking, on this surface. When the surface formed with such cracks is caused to abut on the developing roller to regulate the thickness of the developer passing through the abutting portion, the flow of the developer is inhibited by these cracks, and then the developer is stuck and adhered to the section of the layer-thinning blade in which cracks are generated. The developer adhering to the cracks of the layer-thinning blade adheres to the layer-thinning blade as time advances. The developer adhering to the layer-thinning blade obstructs the passage of the developer passing through the abutting portion from behind the layer-thinning blade, thus fluctuation occurs in the amount of developer passing through the abutting portion regulating the thickness of the developer. Specifically, the amount of developer passing through the section of the layer-thinning blade where the developer adheres is reduced. For this reason, stripe-like image noise is generated in an image corresponding to the developing roller surface that faces the section of the layer-thinning blade to which the developer adheres. Even if the curvature radius of the bent portion has not been changed, the state in which cracks occur due to the image noise varies according to the material of the plate-like member.
In order to remove the cracks of the bent portion, there are methods for performing buffing or other mechanical polishing, chemical polishing, electrolytic polishing and the like to obtain a smooth surface, but the problem is that any of the methods require facilities and processing time, which results in a significant increase in the production cost.